The invention concerns a device on a slider crank for the purpose of generating a motion relative to the slider of a part supported on the slider.
For powering an ejector pin on the die of a forming press, it has been a familiar technique for quite some time to introduce, from the outside, a motion into the slide that is reciprocal to the return travel of the press slide in order to eject the workpiece from the pressing die, such as hexagonal head dies, by means of an ejector pin. Due to the many components between the point of introduction of the force and the ejector, such systems are very elastic. In addition, they also usually involve reciprocating movements.
The device known from DE 195 21 041 A1 has the purpose of reducing this mechanical complexity. This device serves for controlling auxiliary devices such as die ejector pins, strippers, or die carriers in an oscillating press ram of single and multi-stage presses. This is accomplished by a cam attached to the crankpin of the crankshaft of a forming press that controls a pushrod sliding inside the connecting rod; via a spring pin, the motion of this pushrod is transferred to the die, causing the tip of the spring pin to eject the workpiece from the die. When the crank performs one revolution, the cam also performs one revolution in relation to the pushrod. The point of contact between the pushrod and the spring pin is in the center of rotation of the bearing pin connecting the connecting rod with the press ram.
In this DE 195 21 041 A1, an oscillating motion is introduced into the slide.
To be sure, DE 34 12 147 A 1 refers to a centric slider crank, with a transmission that also consists of rotating parts (intermediate gear wheel 24, gear wheel 25), but with one gear wheel (25) fixed on a crank pin (16) that rotates in a crank disk (12) with a centric drive shaft (13); however, part of this transmission is a stationary gear wheel (18) that is coaxial in relation to the shaft axis, and also a rotating gear wheel (23) supported on the crank disk (12) that is located between the stationary gear wheel (18) and the rotating gear wheel (25), and meshes with both of them.
That means that a rotary motion of the crank disk (12) causes a rotary motion of the crank arm (15) relative to the rotated crank disk (12), with said motion depending not only on the crank radius but also on the gear ratio (e.g. 2:1) of the stationary gear wheel (18) and the rotating gear wheel (25). Moreover, this familiar type of transmission does not extend, via the crank arm 15, to the slide (4), so that the generation of a motionxe2x80x94relative to the slidexe2x80x94of a part (such as the slide bar 28) supported on the slide (slider) was not part of the considerations at all.
This is also true for DE-GM 1 864 599 (FIGS. 3 and 4) where, in order to produce two superimposed motions of the pushrod (pushrod 9), on the crank side this pushrod is supported by means of an additional cam (8) on a gear wheel (6) on the main cam (crank pin 5), with the gear wheel (6) meshing with a centrically stationary gear wheel (7).
This invention now addresses the problem of eliminating the disadvantages described above by producing a rotary motion.
Starting with a device of the type referred to at the beginning, the invention solves this problem by means of a slider crank with a device for the purpose of generating a motion relative to a slider of a part supported on the slider, with said motion being taken off a crankpin upon rotation around a crankshaft axis and transmitted along a connecting rod to the part from which an operating motion is taken off, characterized by the feature that in order to generate a rotary motion of that part on the slider around a single axis of rotation relative to both the slider and the connecting rod, a transmission consisting of revolving parts is provided on the connecting rod.
Due to the fact that the rotary motion is transmitted from the crankshaft along the pushrod of the slider crank into the press slide, and that the operating motion is derived directly from this press slide, the invention can be applied universally and makes it possible to transmit large transmission forces in a direct power flow to the operating motion required in each case. Since, except for the tool movement, no additional sliding motions but only rotary motions are involved in transmitting the motion, the device proposed by the invention operates with extremely little wear.
All motions can be produced that can be derived from a rotary motion via appropriate gears.